Safety device for a system of hydraulically transporting solid matters

ABSTRACT

In a system of hydraulically conveying solid matters adapted to hydraulically transport a mixture of the solid such as wood chip or wood bark through a pipeline to a destination, a safety device which comprises a pressure liquid tank containing a pressure water or liquid and a pressure air or gas therein, and a pressure liquid supply line communicating said pressure liquid tank with the pipeline. Said safety device permits the liquid contained in said pressure liquid tank to be delivered through said pressure liquid supply line to the pipeline in case of emergency with the help of the expanding pressure of the air or gas in said pressure liquid tank.

United States Patent [191 Shimizu et a1.

[ Nov. 27, 1973 SAFETY DEVICE FOR A SYSTEM OF HYDRAULICALLY TRANSPORTINGSOLID MATTERS [75] Inventors: Toyotaro Shimizu, Kenichi Mizuno, both ofTokyo, Japan [73] Assignee: 0 J I Paper Co., Ltd., Tokyo,

Japan [22] Filed: Nov. 16, 1971 [21] Appl. No.: 199,107

[52] US. Cl. 302/15, 417/40 [51] Int. Cl. B65g 53/30 [58] Field ofSearch 302/14, 15, 66;

[56] References Cited UNITED STATES PATENTS 3,608,975 9/1971 Sawyer cta1. 302/66 Domecki 417/40 X Regan et al 137/207 PrimaryExaminer--Richard E. Aegerter Assistant Examiner-+1. S. LaneAttorney-Stevens, Davis, et al.

[5 7] ABSTRACT In a system of hydraulically conveying solid mattersadapted to hydraulically transport a mixture of the solid such as woodchip or wood bark through a pipeline to a destination, a safety devicewhich comprises a pressure liquid tank containing a pressure water orliquid and a pressure air or gas therein, and a pressure liquid supplyline communicating said pressure liquid tank with the pipeline. Saidsafety device permits the liquid contained in said pressure liquid tankto be delivered through said pressure liquid supply line to the pipelinein case of emergency with the help of the expanding pressure of the airor gas in said pressure liquid tank.

2 Claims, 3 Drawing: Figures SAFETY DEVICE FOR A SYSTEM OF HYDRAULICALLYTRANSPORTING SOLID I MATTERS This invention relates to safety devicesfor a system of hydraulically transporting solid matters such as woodchip or wood bark, and more particularly it deals with a safety deviceof the type described which permits to hydraulically transport a largequantity of solid matters safely and positively ever a long distancewhile permitting to minimize the volume of the pressure water tank usedto attain the end.

The hydraulic transportation system as means of transportation has along history. In recent years, the demand for rationalization oftransportation has expanded the scope of use of hydraulictransportation, with a result that there is now a demand for a newmethod of carrying the system into practice. Besides, the use of thissystem for transporting goods over an extraordinarily long distance isdesired, and the goods transported by this system have been greatlyincreased in type and number. Hydraulic transportation of wood chips,masses, capsulated materials and the like which have not hitherto beenhandled by this transportation System has made a remarkable progress.

Also, a method has been developed which is intended not only tohydraulically transport solid matters but also to extract usefulconstituentes from solid matters and release the same into the fluidwhile hydraulically transporting the solid matters, to cause a reactionto take place between the solid matters and the fluid used as means oftransportation while the former are being transported by the latter, andto subject the solid matters to a physical or chemical treatment whilebeing transported. Thus, the hydraulic transportation system has madegreat strides in recent years and it is now used not only as means fortransporting solids or slurries but also as new means of materialtreatment born of technical innovation.

The present invention will now be explained with reference to theaccompanying drawing, in which:

FIG. 1 is a systematic view of a piping of the safety device accordingto this invention;

FIG. 2 isa systematic view of a modified form of piping of the safetydevice according to this invention; and

FIG. 3 is a systematic view of a piping of the prior art.

In the embodiments described herein, the safety device according to thisinvention is described as being used with a hydraulic conveying systemwhich involves water and solid matters. It is to be understood, however,that the invention is not to be construed to be limited to the systemwhich uses water alone as a transportationmedium, and that the inventionis applicable to such system of transportation which uses other liquidsthan water.

way is fed to the transportation pump 3a which pumps out the mixtureinto the transportation pipeline 4 for hydraulically transporting thesolid matters to the destination. There are other systems of hydraulictransportation. One of them uses a fresh waterpump and solid matters aresupplied to the delivery side of such pump through rock-hopper feedsystem for transporting the solid matters hydraulically as is generallydone. Other system uses a reciprocating pump, in place of a centrifugalpump, as the transportation pump. Essentially, these systems are nothingmore than modifications of the basic system shown in FIG. 3.

Safety devices for such hydraulic transportation systems must have astheir primary aim the prevention of clogging of the transportation lineby Sedimentation of the solids as a result of reduction in the rate offlow of the mixture of water and solid matters. To this end, thefollowing measures have higherto been taken.

A. First of all, a high reliability is imparted to a power source foroperating the pump so that there may be no failure of power at alltimes. For example, two power sources may be used or a power sourcevoltage may be introduced directly from more reliable high-tensionlines;

B. In case the measure described above is not considered satisfactory insecuring a high degree of reliability of power supply, an emergencypower source installation is provided to switch to non-utilitygeneration for power supply in case of emergency;

C. Means is provided for switching quickly and readily to the, reservepump 3b from the transportation pump 3a so as to cope with the hitch ortrouble of pump 3a or its drive motor;

D. In case the measures described above in A, B and C are not consideredsatisfactory in securing a high degree of reliability of power supply,the reserve pump 3b or both the transportation pump 3a and reserve pump3b are made independent of the electric power source FIG. 3 shows apiping of a hydraulic conveying sys- I tern of the prior art. In thefigure, l is a mixing tank, 2 an agitator, 3a a hydraulic transportationpump, 3b a reserve pump, 4 a pipeline for hydraulic transportation, 5 amain supply valve of solid-water mixture, 6 a main shut-off valve, 7 ablow-out valve for the mixing tank,

I 8 discharge branch lines, and .9 emergency discharge by driving themwith diesel engines, gasoline engines or steam turbines etc.; and

E. In case the measures described above in A, B, C and D are notconsidered satisfactory in securing a high degree of reliability of thetransportation system, a plurality of branch lines 8 are provided insuitable positions in the pipeline as shown in FIG. 3 and the emergencydischarge valves 9 are opened in case of emergency by remote control todischarge the flow of mixture to sewage or nearby rivers for preventingthe clogging of the pipeline.

The aforementioned safety devices will all have effect if the mixture ofsolid matters and water has a relatively low volumetric concentration(the ratio in volume of the Solid matters to the mixture of solidmatters and water) and the flow of such mixture is substantially like aflow of liquid or slurry as is the case when the mixture handledconsists of materials in the form of pulverized materials or slurriesand water. However, such safety devices are unable to producesatisfactory results when the hydraulically transported solid mattersare complex in shape, relatively large in size and the mixture of suchsolid matters and water has a high volumetric concentration and cannotbe regarded as a fluid as it is the case with hydraulic transportationof pulpwood chips or wood barks.

Morespecifically, when solid matters complex in shape and large in sizeand having a high volumetric concentration is transported hydraulically,the pump is liable to be jammed in its inner parts (in gaps between theblades of pump runner, for example) with the solid matters even if thepump-drive-means or pump itself is in operation. In such case, thesafety devices described in paragraphs A, B, C and D are of no avail.

Also, when hydraulic transportation of such solid matters of highvolumetric concentration is carried out, cessation of flow of themixture of solid matters and water even for a very short time intervalof several to ten-odd seconds results in clogging of the pipeline, so

that it is not desirable to permit the rate of flow to be reduced belowa predetermined level (which is referred to as a critical flow rate)even for an instant, This makes it substantially impossible to smoothlyswitch from the pump that has troubled to a reserve pump in case ofemergency.

Furthermore, when such solid matters of high volumetric concentration istransported hydraulically, it is not possible to discharge the mixtureof solid matters and water in uniform flow even if the facilities(branch lines 8 and discharge valves 9 of FIG. 3) described in paragraphE are provided. In such case, a dehydration phenomenon is liable tooccur. When any of the discharge branch-lines is opened in case ofemergency, the mixture of solid matters and water may be dischargedthrough such branch line for some time after the branch line is opened.However, as the rate of flow of the mixture in the pipeline is reduced,movement of the solid matters is retarded while the rate of flow ofwater is not considerably reduced, with a result that the concentrationof the mixture discharged through the branch line is rapidly reducedtill finally only the water is discharged. Thus, only the solid mattersremain stationary in the pipeline, thereby making it impossible torestart flow of the mixture. Besides, draining of the hydraulicallytransported solid matters into sewage or rivers is not only undesirablebecause of solid matters losses but also liable to cause a publicnuisance. Thus, discharging of the mixture of solid matters and waterthrough discharge branch lines involves various problems difficult toobviate,

The present invention obviates the aforementioned disadvantages. Theinvention has as its object the provision of a safety device whichpermits to carry out hy'- draulic transportation of various types ofsolid matters without any trouble.

According to this invention, there is provided a safety device for asystem of hydraulically transporting solid matters which represent adeparture in concept from the safety devices of the prior art describedabove. The safety device provided by this invention permits to maintainthe flow rate of the mixture of solid matters and water aboveapredetermined safety level at all times by detecting beforehand anoccurrence of emergency and supplying automatically fresh water or otherliquid in place of the mixture, so that the flow rate of the mixture canbe dept at a constant level by purging with pressure water and cloggingof the pipeline can be prevented by replacing the mixture in thepipeline by the fresh water or other liquid.

More specifically, the safety device according to this invention is suchthat it can detect all the abnormalities in the hydraulic transportationsystem, such as disabling of the power source for operating the pump,deviation from the normal pressure differential between the inlet andthe outlet of the pump, a reduction in the flow rate of the mixture inthe pipeline and the like, and

the pressure water main valve provided at the inlet of the pipeline isopened when any of such abnormalities is detected so as to ensure thatthe mixture in the pipeline is transported and purged by means of thepressure water and the flow rate of the mixture is not reduced below acritical level at all times. I

FIG. 1 shows one embodiment of this invention, and reserve pumps of thisembodiment are omitted in the interest of brevity. Like referencecharacters designate similar parts mall the drawings.

The hydraulic transportation system shown in FIG. 1 is similar to theconventional hydraulic transportation system shown in FIG. 3 except thatin the former a pressure water supply line 10 is connected to thepipeline 4 in a position which is delivery side of the pump 3 and themain shut-off valve 6 for maintaining communication between the pipeline4 and a pressure liquid tank 12 containing water or other liquid underpressure, and a fresh water or other liquid supply line 16 is connectedto the line 10. A pressure water stop valve 11 and an adjusting valve20a are provided in the pressure water line 10, and the pressure watertank 12 is maintained in communication, through a pipe 21 mounting apressure reducing valve 14, with a compressed air receiver tank 13 whichin turn is maintained in communication with a compressed air sourcethrough a pipe 15.

The fresh water supply line 16 is connected to a fresh water reservoir18 through an adjusting valve 20b and an emergency fresh water pump 17.Provided in the pipeline 4 is a flowmeter 19 which is connected to asuitable servomechanism for controlling the valves and pumps of thelines connected to the pressure tank and fresh water tank respectivelyin accordance with the read-out values of the flowmeter.

In operation, water or other liquid and solid matters to be transportedare fed into the mixing tank 1 and agitated therein so that they may bemade into a uniform mixture of any concentration which is delivered tothe pipeline 4 by the pump 3 and transported hydraulically to itsdestination. The flow rate of the mixture in the pipeline 4 is measuredby the fiowmeter 19 at all times so that the system may be operatednormally except when the flow rate is reduced below a critical rate.

In case of emergency or when a reduction in the flow rate is detected bythe flowmeter 19, the pressure water main valve 11 is immediately openedand at the same time th pipeline shut-off main valve 6 is closed so asprovisionally to fill the pipeline 4 with a supply of water from thepressure water tank 12 and maintain the flow rate of mixture therein ata predetermined level. While this is in progress, the emergency freshwater pump 17 is actuated at once so that a supply of fresh water isdelivered under pressure by the fresh water pump 17 to the pipeline 4and then the mixtures in the pipeline are purged and replaced graduallywith the fresh water from the fresh water reservoir 18. Thereafter, thepipeline 4, pump 3 and other parts can be inspected or the machines usedcan be switched to reserve machines.

Now we assume that a mixture of wood chips and water having a volumetricconcentration of about 25 to 30 percent is hydraulica ly transportedthrough a pipeline made of steel and having a diameter of 8 inches at anaverage flow velocity of 2 meters per second with an average flow rateof 4 cubic meters per minute and a critical flow velocity is 0.7 meterper second, and in case of emergency the flow rate in the pipeline mustbe 1 maintained at the predetermined average level by a supply ofpressure water from the pressure water tank for about 2 minutes andthereafter a supply of fresh water may be. delivered under pressure tothe pipeline from the fresh water reservoir by means of the emergencyfresh water pump 17. In such case, a tank of small capacity or aboutcubic meters may be used as the pressurewater tank 12.If the emergencyfresh water pump 17 is driven by a diesel engine or gasoline engine, itcan be started within 30 seconds, making it possible toquickly switchfrom one source of supply of pressure water to another source".

If the delivery pressure of the pump is 6 kg/cm by assuming that thetransportation distance of the mixture is about 3 kilometers, only onecompressed air receiver 13 havig a capacity of cubmic meters may beprovided by using a compressed air of 19 kg/cm.

If no emergency fresh water pump 17 were provided and the mixture wereto be transported and purged through the pipeline 4 over the entiredistance of 3 kilometers only by a supply of pressure water from thepressure water tank, the pressure water tank 12 would have to have acapacity of no less than 100 cubic meters. If the pipeline for hydraulictransportation covered a longer distance or had a larger diameter, itwould be almost impossible because of large capacity of the pressurewater tank 12 to carry out hydraulic transportation and purge of themixture referred to hereinabove only by a supply of pressure water fromthe pressure tank. It is to be understood that, if the distance to becovered were short or the pipeline had a smaller diameter and themixture to be transported has which provides particularly against thesolid matters being bitten by the main shut-off valve 6 when it isclosed in case of emergency. I

When wood chips or wood barks are transported hydraulically, nodifficulty is faced with in quickly opening the pressure water mainvalve 11 shown in FIG. 1, but the closing of the pipeline shut-off mainvalve 6 is often closed incompletely because there is thedanger of woodchips being bitten by the valve body, thereby making it impossible tofully shut-off the pipeline.

In order to obviate this disadvantage, the safety device according tothis invention comprises, in another aspect, two shutoff main valves 6aand 6b shown in FIG. 2, in place of one main valve 6, which are arrangedin series and spaced apart from each other a proper distance; thepressure water main line 10 is connected to the pipeline 4 in a positioninterposed between the two shut-off main valves 6a and 6b; a branch line22 of the pressure water main line 10 is connected to the pipeline 4 ina position which is disposed opposite the main line 10 connected withthe pipeline 4 with respect to the second shut-off main valve 6b; andpressure water stop valves 11a and 11b are mounted in parallel with eachother in the pressure water main line 10 and branch line 22respectively.

In case of emergency, the pressure water stop valve 11a is quicklyopened and shut-off main valve 6a is closed so as to pennit a supply ofpressure water to be delivered through the main line 10 to the pipeline4 to a degree such that the mixture of solid matters and water in aportion of the pipeline 4 near the shut-off main valve 6b is replaced bythe fresh water under pressure. When this .is accomplished, the pressurewater stop valve 11b is opened and at the same time the valve 11a andthe main valve 6b are closed. This permits to deliver a supply ofpressure water from the pressure water tank 12 to the pipeline 4 throughthe pressure water branch line 22, while a portion of the pipeline 4from its connection to the tank 1 to the pump 3 is completely isolatedby the stop valve 6b from the remainder of the pipeline 4, so as tothereby prevent the clogging of the pipeline 4. Thus, the provision ofthe two shut-off main valves 6a and 6b is effective to fully cut off thepipeline 4 from the tank 1 and the pump 3 by closing the second mainvalve 6b in case the first main valve 6a is incompletely closed due towood chips being bitten by the valve 6a.

In the embodiments described hereinabove, the pressure water tank 12 isconnected to a compressed air receiver or an air compressor. It is to beunderstood that the pressure water tank 12 could altematively beconnected to a high pressure gas holder or gas pressure producing deviceof considerable capacity so as to use the gas pressure for producingpressure water for transporting and purging the mixture in the pipeline.

The pressure water tank 12 may be supported at a great height toincrease the natural water head more than the necessary pressure of thepressure water which is supplied from the tank 12. If this is the case,the compressed air receiver, compressor and the like can be eliminated.

From the foregoing description, it will be appreciated that the safetydevice according to this invention comprises features which offer manyadvantages. The feature of maintaining the pipeline in communicationwith the pressure water or pressure liquid tank through the pressurewater or pressure liquid supply line which is connected at itsintermediate portion to the fresh water or liquid supply system iseffective to carry out safety hydraulic transportation of a mixture ofsolid matters and water without any trouble at all times, because thisfeature permits to first deliver a supply of pressure water. or liquidto the pipeline and then switch from the supply of pressure water orliquid to a supply of fresh water or liquid and transport and purge themixture in the pipeline in case of emergency so as to prevent thecloggingof the pipeline. Since the pressure water or liquid tank isrendered operative only in initial stages of emergency case and switchedimmediately to the fresh water or liquid supply system, a tank of asmall capacity can be used as the pressure water or pressure liquidtank.

The feature of installing the two shut-off main valves in series witheach other in the pipeline and providing the two pressure liquid stopvalves in parallel with each other in respective pressure liquid supplylines connected to the pipeline immediately posteriorly to the shut-offmain valves permits to completely cut off the pipeline from the mixingtank and the pump in case of emergency in spite of the fact that woodchips, wood barks or other solid matters of relatively large size mixedwith water or liquid are liable to be bitten by the valve body. This iseffective to transport and purge the mixture of body matters and liquidin the pipeline in case of emergency, and permits to carry out safelyhydraulic transportation of a mixture of solid matters and liquid havinga high volumetric concentration in a great volume over a long distancewithout any trouble.

We claim:

1. in a system of hydraulically conveying solid matters such as woodchip or wood bark through a pipeline to a destination, a safety devicewhich comprises a pressure liquid tank containing a pressure water orliquid and a pressure airor gas therein, two main shut-off valvesinstalled in series with each other in the pipeline, a pressure liquidsupply line communicating said pressure liquid tank with the pipelinebetween said two main shut-off valves, a pressure liquid supply branchline from an intermediate portion of said pressure liquid supply lineconnecting a portion of the pipeline which is disposed opposite theconnection of said pressure liquid supply line to the pipeline withrespect to one of said two main shut-off valves, and two pressure liquidstop valves installed in parallel to each other in the pressure liquidsupply line and the pressure liquid supply branch line respectively,which permits one of said main shut-ofi' valves to be closed completelyand the liquid contained in said pressure liquid tank to be injectedthrough said pressure liquid supply line to the pipeline in case ofemergency with the help of the expanding pressure of the air or gas insaid pressure liquid tank whereby the flow rate of the mixture in thepipeline can be maintained at a predetermined level.

2. In a system of hydraulically conveying solid matters such as woodchip or wood bark through a pipeline to a destination, a safety devicewhich comprises a pressure liquid tank containing a pressure water orliquid and a pressure air or gas therein, two main shut-off valvesinstalled in series with each other in the pipeline, a pressure liquidsupply line communicating said pressure liquid tank with the pipelinebetween said two main shut-off valves, a liquid feed system connected tosaid pressure liquid supply line at an intermediate portion thereof, apressure liquid supply branch line from an intermediate portion of saidpressure liquid supply line connecting to a portion of the pipelinewhich is disposed opposite the connection of said pressure liquid supplyline to the pipeline with respect to one of said two main shut-offvalves, and two pressure liquid stop valves installed in parallel toeach other in the pressure liquid supply line and the pressure liquidsupply branch line respectively, which permits one of said main shutoffvalves to be closed completely and the liquid contained in said pressureliquid tank be first injected through said pressure liquid supply lineto the pipeline in case of emergency and then a liquid to be fed to thepipline through said liquid feed system, whereby the flow rate of themixture in the pipeline can be maintained at a predetermined level.

1. In a system of hydraulically conveying solid matters such as woodchip or wood bark through a pipeline to a destination, a safety devicewhich comprises a pressure liquid tank containing a pressure water orliquid and a pressure air or gas therein, two main shut-off valvesinstalled in series with each other in the pipeline, a pressure liquidsupply line communicating said pressure liquid tank with the pipelinebetween said two main shut-off valves, a pressure liquid supply branchline from an intermediate portion of said pressure liquid supply lineconnecting a portion of the pipeline which is disposed opposite theconnection of said pressure liquid supply line to the pipeline withrespect to one of said two main shut-off valves, and two pressure liquidstop valves installed in parallel to each other in the pressure liquidsupply line and the pressure liquid supply branch line respectively,which permits one of said main shut-off valves to be closed completelyand the liquid contained in said pressure liquid tank to be injectedthrough said pressure liquid supply line to the pipeline in case ofemergency with the help of the expanding pressure of the air or gas insaid pressure liquid tank whereby the flow rate of the mixture in thepipeline can be maintained at a predetermined level.
 2. In a system ofhydraulically conveying solid matters such as wood chip or wood barkthrough a pipeline to a destination, a safety device which comprises apressure liquid tank containing a pressure water or liquid and apressure air or gas therein, two main shut-off valves installed inseries with eAch other in the pipeline, a pressure liquid supply linecommunicating said pressure liquid tank with the pipeline between saidtwo main shut-off valves, a liquid feed system connected to saidpressure liquid supply line at an intermediate portion thereof, apressure liquid supply branch line from an intermediate portion of saidpressure liquid supply line connecting to a portion of the pipelinewhich is disposed opposite the connection of said pressure liquid supplyline to the pipeline with respect to one of said two main shut-offvalves, and two pressure liquid stop valves installed in parallel toeach other in the pressure liquid supply line and the pressure liquidsupply branch line respectively, which permits one of said main shut-offvalves to be closed completely and the liquid contained in said pressureliquid tank be first injected through said pressure liquid supply lineto the pipeline in case of emergency and then a liquid to be fed to thepipline through said liquid feed system, whereby the flow rate of themixture in the pipeline can be maintained at a predetermined level.